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I didn't put a switch in the cockpit. My system came with an enclosure with the BMS mounted which included a switch, alarm, and a reset button. I just removed everything and mounted it near the battery. The switch disconnects the battery by using a contactor on the positive cable. My system has only 1 set of cables for charging or pulling power. The multiple terminals on the cells would allow a separate charging input and inverter draw. Since I'm using my existing inverter which also charges through the same cables I only have 1 contactor. If you design your system from scratch you can use a contactor on each set of cables to either shut down the inverter on low voltage or shut off your charger on high voltage. My system is not as adaptable but still works well. My BMS is the Housepower system not Balqon. They just supplied it with my cells. My BMS doesn't control the charging, it just monitors each cell voltage and shuts off the battery system on either low or high voltage. I'm not sure how each charging source would work together. The trick would be to get each source outputting its maximum without exceeding the high voltage set point on the BMS. It took me quite a lot of work to get my inverter to charge without exceeding this point which is 14.2 on the Housepower BMS.
My alternator regulator is set up to float at 13.2 v which should basically turn it off. But I haven't had the coach on the road yet since installing the regulator so may have to adjust it if this doesn't work. My wife doesn't know it yet but she'll be spending a lot of time watching the battery monitor over the microwave
The Balmar does have the capability to do what you want but I'm not planning to use that capability. I'd suggest to read up on the www.cruisersforum.com and search for user Maine Sail. He is one of those who has done a lot of research on the Balmar.
I'm not sure how to hook up a solar system in conjunction with the other charging sources. Again some of the guys on www.cruisersforum.com are doing this.
For the catastrophe fuse I'm using the same one that was installed in the coach for the agms. I believe it is a 400amp. Your system if all charging sources are outputting maximum would still be less than 0.5C so shouldn't be a problem for the cells.
But please remember I am not an expert at these. I'm learning as I go so please don't rely on my suggestions without doing additional research to make sure you understand what you're doing.
Hope this helps.